Bind mount no longer working in 21.1 in fstab

Turbocapitalist · 01-15-2023, 09:45 AM

I used to have have a bind mount which worked via /etc/fstab across a variety of different distros:

Code:

/var/tc/music      /home/tc/Music     none defaults,bind 0 0

After moving to Linux Mint 21.1, the above setting no longer properly bind mounts the directory. Instead it seems to do something wrong with it:

Code:

$ mount | grep Music
/dev/nvme1n1p2 on /home/tc/Music type ext4 (rw,relatime,stripe=32)

If I remove the fstab entry, I can manually bind mount the directory just fine.

Code:

mount --bind /var/tc/music /home/tc/Music

I even tried cargo culting the following undocumented settings into fstab and rebooted, and no improvement:

Code:

/var/tc/music   /home/tc/Music  auto    bind,x-gvfs-hide,x-systemd.requires=/var   0       1

and

Code:

/var/tc/music   /home/tc/Music  auto    bind,x-gvfs-hide,x-systemd.requires=/home   0       1

Those just cause the booting to fail by causing / to mount read-only.

One thing different is that the /home is in an OpenZFS mirror

Code:

$ mount | grep home
home on /home type zfs (rw,xattr,noacl)

$ zpool status
  pool: home
 state: ONLINE
config:

        NAME           STATE     READ WRITE CKSUM
        home           ONLINE       0     0     0
          mirror-0     ONLINE       0     0     0
            nvme0n1p4  ONLINE       0     0     0
            nvme1n1p4  ONLINE       0     0     0

I think the work-around is just to use symlinks instead of bind mounts but I would really like to figure out what the right way to bind mount in fstab is in Linux Mint 21.1

pan64 · 01-16-2023, 02:58 AM

According to the man page you only need: /olddir /newdir none bind
If I need to guess /var/tc/music should be mounted first so you need to specify that, but I'm not really sure. Would be nice to check the logs (dmesg/journalctl?) to see what's going on during boot.

Turbocapitalist · 01-16-2023, 03:17 AM

Quote:

Originally Posted by pan64

According to the man page you only need: /olddir /newdir none bind

The manual page mentions very little, but the line used to work in earlier versions of Linux Mint and PepperintOS and Devuan and so on. However with those, there was no use of OpenZFS for the home partition and there seems to be more systemd than ever in 21.1.

Quote:

Originally Posted by pan64

If I need to guess /var/tc/music should be mounted first so you need to specify that, but I'm not really sure. Would be nice to check the logs (dmesg/journalctl?) to see what's going on during boot.

That's close to my guess too. Both /var (where /var/tc/music resides) and /home need to be mounted before the bind can take place. The output from dmesg doesn't show any problem with the main partitions, that I can tell, and does not mention ZFS. What should I look for in the output of journalctl -xe?

pan64 · 01-16-2023, 04:01 AM

you need to look for anything related to /var/tc/music and/or /home/tc/Music (including the order of events).
After a reboot, without manual bind you may also try systemctl status <mount service> or similar to check them